Implement ServiceGatewayClient::ErrorResponse#to_h

Used to propagate errors to cf client.
Bump to 2.2.2
Nest backtrace and types inside gateway error hash

This brings the format of CC errors in line with that of the V1
gateways.
Add Windows support for cpu load average and system memory.
Refactor code from component private methods for Windows statistics (memory / cpu) to WinStats class with tests.